The invention relates to a spring-biased locking bolt. Such spring-biased locking bolts are used for a locking connection between two associated elements for general applications in machine tools and furniture manufacturing. A spring-biased locking bolt of this type is essentially made of an operating button that is firmly attached to an approximately cylindrical bolt that extends through a sleeve, with a screw thread arranged on the bottom end of the sleeve.
The screw thread is used to insert the sleeve into an opening located on an item of furniture or a machine part, whereby the bolt that is attached to the operating button extends through the opening into the item of furniture or machine part and engages with an additional opening in an opposing part aligned with the opening. The locking bolt can thereby be used to connect two related parts with each other.
The connection between the two parts is released by pulling on the operating button. The bolt is thereby pulled out of the corresponding opening in the opposing part against the spring force.
Spring-biased locking bolts with an operating button that includes a catch have also been reported. The catch causes the operating button to remain in the pulled-out position after it has been pulled out. The bolt that is connected with the operating bolt is thus permanently disengaged from the opening in the machine part or item of furniture, and the connection between the two parts is severed.
In another embodiment, the catch includes two opposing projecting pins arranged on the bottom side of the operating button and extending in the axial direction. In the locked position, the pins contact the upper end face of the spring-biased sleeve.
The latching engagement is produced by pulling the operating button out of the sleeve against the spring force and rotating the operating button until the pins arranged on the bottom side of the operating button make contact with the upper end face of the sleeve. In this position, the operating button is locked, and the pin connected with the operating button is permanently disengaged from the corresponding opening on the machine part or item of furniture.
Conversely, in the locked position, the pins located on the bottom side of the operating button engage in slots arranged in the wall of the sleeve.
A spring-biased locking bolt of this type has the disadvantage that the two pins attached on the operating button are not very strong and can easily break off.
Moreover, the entire locking arrangement is exposed and susceptible to contamination. The guide sleeves disposed in the slots also adversely affect the axial longitudinal guiding of the pins that extend through the guide sleeve. Due to the slots extending through the wall of the sleeve, the opening in the guide sleeve is no longer completely round (cylindrical), but is broken up by the slots arranged along the circumference. As a result, the locking bolt has an undesirable radial play, causing the opening to wear out faster.
This arrangement also diminishes the visual appearance, because the pins on the bottom side of the operating buttons are visible from the side. The manufacturing cost for an operating button are also relatively high, because forming dimensionally stable pins on the bottom side of the operating button requires a more complex cutting process in manufacture, which is also the case when producing a mold tool if such part is to be made out of plastic or cast metal.
Because the pins attached on the bottom side of the locking bolt are visible from the side, they can also be easily damaged. For example, a pin can be sheared off or break off, thus destroying the locking functionality of the spring-biased bolt.
A simpler embodiment of a spring-biased locking bolt has also been disclosed, which lacks the aforementioned catch between the spring-biased movable sleeve and the operating button.
In this simpler embodiment, the spring-biased sleeve is guided on the bolt that is connected with the operating button. This simplified embodiment, however, cannot be modified to include an additional catch.